Contaminated Round Bale Haylage Blamed for 100 Surrogate Mares’ Deaths on Florida Embryo Transfer Farm

State officials and veterinarians in the Ocala, Florida region are investigating a massive death event at an embryo transfer farm near Summerfield. In the past 10 days, dozens of broodmares began showing neurological signs of distress, and often dropped dead in the fields. About 100 horses are believed to be dead.

The farm owners believe the cause to be something in haylage bales, which they purchase from an outside contractor. The farm, which houses 400 “rescued” mares used in embryo transfer services, is the contractor’s sole customer, so it is hoped that whatever contaminated the bales was limited to that source.

“[The horses] started trembling and fell on the ground. It was like they were having seizures,” said the farm owner, who is also a veterinarian and said that attempts were being made to determine the cause of the horses’ deaths.

Moldy hay is a common problem with horses. Dead animals can contaminate hay as well, but probably would not be present in so many bales. That leaves the possibility of botulism.

Dr. Carol Clark, a veterinarian with Peterson & Smith Equine Hospital in Ocala, provided background information. In the case of botulism, the bacteria Clostridium botulinum produces spores, which stick to the hay when it is cut and baled. The spores become bacteria, which produce a deadly toxin. The bacteria thrive in environments absent of oxygen. In some cases, grass that is cut and wrapped begins to ferment, which is conducive to the deadly bacteria’s growth if not handled correctly, Clark said. She commented that the processed hay (“haylage”) is typically given to cattle because they are less susceptible to botulism.

The veterinarian/owner said the hay he gave his sick horses was haylage, but that it was “inoculated” to make it safe for horses.

According to an information paper from the government of Ontario on haylage for horses, the warning signs of botulism are that affected horses:

  • usually have muscle tremors.
  • may be so weak that they cannot stand up.
  • lose control of their tongue so it may hang from their mouth.
  • can’t eat and they drool because they can’t swallow.
  • may walk stiffly with a short stride or they may be weak and stumble. Their tail may lose its tone.

Please read the complete information paper if you are hoping to save on your hay budget and feed haylage to horses. There are specific commercial haylages made just for horses, with particular grasses and harvesting techniques.

A mysterious footnote to the botulism theory is that it is standard procedure for broodmares to be vaccinated against botulism, since young foals are highly susceptible to the infection.

In an interesting twist of events in this story, a representative of the State of Florida said that it would not be involved because it only investigates health problems related to horse feed, not grass-based hay.

The farm, known as EquiTransfer, is home to about 400 mares, primarily surrogate “receiver” mares, who are used in embryo transfer services provided by the farm, which technically leases the mares for the purpose of carrying another mare’s foal and giving birth. One of the owners commented that the farm used “rescued” mares. In 2006, the farm performed 700 embryo transfers and, according to its website, is the largest embryo transfer farm in the Southeast. The farm seems to specialize in breeding Paso Fino horses, plus some Gypsy Vanners, via mare surrogates of any and all breeds. reports that there had been complaints from local citizens about the condition and welfare of the mares but that no action had been taken by authorities.

Farms like EquiTransfer are increasingly coming under criticism by animal welfare advocates as being the horse equivalent of puppy mills for dogs. One mare can provide several embryos per year although opponents warn that repeated breeding and flushing may put the mare at risk for infection, as well as saturating the market and decreasing the gene pool for breeds for which it is a popular practice. However, sabotage is apparently not suspected.

“It was a surprise to everyone. It was an isolated incident. It’s very sad. We rescued those horses to be surrogate mothers,” said one of the owners on a local television broadcast.

Click here to watch a video news reports from Central Florida’s WFTV. Read an article in today’s Gainesville Sun about this tragedy here.

Blogger’s Comment: Information for this post was provided via an alert from the RSOE Emergency and Disaster Information Service. (Thank you!) It is rare for one news story to touch on or hint at so many of the pressing issues in the horse industry today: cost cutting measures on farms, vaccination procedures, feed safety, veterinary ethics, farm management, horse rescues, the cost of hay, market breeding, consumer protection (or lack thereof), ethics of breeding, overbreeding, puppy mills: It’s all there. As I was investigating this story, I became more and more amazed. I imagine I will write more stories in the months to come about poisoning of horses from contaminated hay. This one, however, will hopefully and probably not be equaled. Photo below courtesy of Flickr close-up expert fivefiveandahalf.




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